The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs.
For example, as optical lithography approaches its technological and economical limits, a directed self-assembly (DSA) process emerges as a potential candidate for patterning dense features such as contact holes. A DSA process takes advantage of the self-assembling properties of materials, such as block copolymers, to reach nanoscale dimensions while meeting the constraints of current manufacturing. Typical DSA processes use a guide pattern that “guides” the self-assembling process. The geometry of the guide pattern may affect the configuration of the self-assembled polymer features, as well as the final pattern density. Improvements in these areas are desired.